512 Sir ^V. Ramsay and Dr. B. D. Steele on the 



Normal Octane. 

 Weight of substance =0-36007 gram. Temperature = 125*6°. 



Volumeinc.es 23913 198'62 15404 133-17 



Pressure in mms 32014 38373 49078 564-74 



-Pv?nT 534-04 531-68 52716 52408 



Weight the same. Temperature= 131-4*^. 



Yolumeinc.es 19890 17507 153-42 132-55 



Pressure in mms 38924 43815 498-31 573-26 



Pi;/iT 531-66 52944 527-66 524-84 



Compressibility. 



Volumeinc.es 57-740 30-386 18-155 11-581 



Pressure in mms. ... 40047 75-893 126-59 198-50 



Factor 023514 0-23514 023514 0-23514 



-PvmT 543-71 542-23 540-40 538-20 



Vv/mT at zero pressure =544-4. 



Di-isobutyl. 



Weight of substance =0-26359 gram. Temperature =129-60°. 



Volume 229-27 202-06 17958 156-40 134-61 94*97 



Pressure 249-57 28267 317-53 363-44 42083 590-45 



Vv?nT 539-83 538-86 537-97 53627 53443 529-03 



Weight the same. Temperature= 114-90°. 



Volume 229-18 201-99 179-53 134-57 94-95 



Pressiu-e 240*03 271*68 304-94 404-01 565-69 



FvmT 538-66 537-37 536-06 532-39 525-96 



Compressibility. 



Volume 46-181 24-316 14-539 9-241 



Pressure 40-047 75-893 126-59 198-50 



Factor 0-29494 0-29494 0-29494 029494 



Tv 7iiT at zero pressure =546-2. 



Inasmuch as the value o£ this research is absolutely de- 

 pendent on the purity of the liquids employed it appears 

 necessary to give a rigorous proof of the fact. Mere con- 

 firmation of the concordance of any two sets of determinations 

 with the same sample of any one substance would be con- 

 vincing only as regards the accuracy of the method ; it is 

 necessary to prove that, at least in several cases, samples of 

 the same substance, differently prepared or differently treated, 

 yield practically identical results. With the substances kindly 

 furnished by Prof. Young redistillation from phosphoric 

 anhydride was the only means of purification which we could 

 attempt, for we had only small amounts at our disposal ; an 

 example of the effect oi: thus treating normal hexane will be 

 found in the following table. It did not appear obvious how 

 w^e could improve on a sample of the purest tbiophene-free 

 benzene of absolutely constant boiling-point which had been 

 purified by frequent recrystallization. Nor could we de^-ise 

 another and better way of obtaining a reliable sample of 

 methyl-alcohol than by hydrolysing methyl oxalate, itself 

 prepared from " pure " methyl-alcohol, and drying the re- 

 sulting alcohol by help of the best lime obtainable. It is 

 true it might have been recrystallized, but as the only likely 



